package likouJava;

public class 对称二叉树 {
    public boolean isSymmetric(TreeNode root) {
        if(root == null)return true;

        return  isMirror(root.left, root.right);
    }

    private boolean isMirror(TreeNode t1, TreeNode t2) {
        if (t1 == null && t2 == null) return true;

        if(t1 == null || t2 ==null) return false;

        return (t1.val == t2.val) && isMirror(t1.left, t2.right) && isMirror(t1.right, t2.left);
    }

}
